Gee, maybe Mexico should have encouraged industrial growth outside of the D.F. ... you know, spread the opportunities and population around.
One of the ancient symbols of Mexico was an eagle with a snake in its beak. It's from the story of how the Aztecs chose the site of Tenochtitlan, the site of modern Mexico City. The eagle is pictures perched on a cactus. The site of Tenochtitlan was on a lake, but the ancient city's population was far less and the D.F. apparently is an arid area.
I know there are California bashers who want to believe otherwise, but California has numerous reservoirs on rivers and creeks, and also uses aquifers for underground storage. Just the water district in which I live - part of Santa Clara County - has over a dozen reservoirs, and the aquifer over which I live is so full that water seeps through a low-lying section of the I-880 freeway. As a whole the state's reservoirs are at 80%-100% capacity, with more snow melt to come.